1. Field of the Invention
Methods and apparatuses consistent with the present invention relate to authentication and an image display apparatus thereof, and more particularly, to an authenticating method which prevents an abnormal screen from being displayed due to High Bandwidth Digital Content Protection (HDCP) authentication error, and an image display apparatus thereof.
2. Description of the Related Art
Widespread distribution of digital images has brought introduction of interface between digital image devices such as settop boxes, DVD players, multimedia sources such as PCs, and video displays such as AV devices, monitors, digital televisions.
Digital interfaces such as Digital Visual Interface (DVI) and High Definition Multimedia Interface (HDMI) are available, and unlicensed copying of digital content through the digital interfaces is prohibited under the specification, High Bandwidth Digital Content Protection (HDCP).
FIG. 1 illustrates the structure of a multimedia source system being connected with an associated video display through a digital interface. Referring to FIG. 1, a settop box 10 is connected with a TV 100 through DVI/HDMI cable.
The settop box 10 detects that it is connected with the TV 100 through DVI/HDMI cable, based on a HPD signal being input from the TV 100. The settop box 10 determines that the TV 100 has a HDCP authentication key, in response to a high HPD signal. Upon determination that the TV 100 has the HDCP authentication key, the settop box 10 outputs digital video data which represent normal screen on the TV 100. If determining that the TV 100 does not have a HDCP authentication key, the settop box 10 outputs scrambled digital video data, which represent abnormal image on the TV 100.
The settop box 10 generally determines the presence of a HDCP authentication key of the TV 100 in every two or three seconds. However, some settop boxes determine that the TV 100 does not have a HDCP authentication key, if the TV 100 is turned on after the settop boxes.
Accordingly, some settop boxes output scrambled digital video data on the TV 100, mistakenly determining that the TV 100 does not have a HDCP authentication key.
The similar mistake can arise when the HDCP authentication of the TV 100 was successful. That is, in certain cases, erroneous authentication information may be transmitted to the settop box 10 or the authentication information may not be transmitted to the settop box 10 at all, due to communication error between the TV 100 and the settop box 10, or by accidental power reset.
Because the settop box 10 erroneously determines that the TV 100 does not have a HDCP authentication key, scrambled digital video data is output on the TV 100 and as a result, abnormal screen is displayed.